OFFSET
0,2
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
FORMULA
From Colin Barker, Aug 14 2017: (Start)
G.f.: (1 + 5*x + 15*x^2 + 5*x^3 + x^4) / (1 - x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n > 4.
(End)
EXAMPLE
1, 2 + 3 + 4, 5 + 6 + 7 + 8 + 9 + 10, ...
MATHEMATICA
CoefficientList[Series[(1 + 5 x + 15 x^2 + 5 x^3 + x^4)/(1 - x)^4, {x, 0, 40}], x] (* Michael De Vlieger, Aug 15 2017 *)
PROG
(PARI) Vec((1 + 5*x + 15*x^2 + 5*x^3 + x^4) / (1 - x)^4 + O(x^100)) \\ Colin Barker, Aug 14 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Enrique Navarrete, Aug 13 2017
STATUS
approved